The central aim of this project is to investigate the effects of increased linguistic demands on speech production in individuals with Parkinson's disease (PD). Speech disturbances are common in PD; however, studies of speech production have primarily focused on perceptual characteristics, instead of on the complex articulatory movements underlying the speech disorder. Furthermore, although a decrease in speech intelligibility is evident during longer productions in individuals with PD, the few studies of speech kinematics in this population were generally based on syllable, non-word, or word-level production tasks. In order to understand how speech movements are affected by PD, it is essential to take into account the linguistic structure and goals of the utterance. Therefore, articulatory movement data from the upper lip, lower lip, and jaw will be collected from 15 individuals with PD and 15 age- and sex-matched neurologically normal adults during speaking tasks that vary in length and linguistic complexity. Measures of speech motor control, behavioral data from language assessments, and perceptual evaluations of speech intelligibility will be analyzed in order to contribute to a comprehensive profile of how communication is affected by PD. This work will have significance for understanding the neural processes related to speech production, and will also have important implications for diagnostic and therapeutic approaches to PD.